138
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
EFFECTS OF SEWAGE EFFLUENT IRRIGATION ON THE
CHEMICAL COMPONENTS AND MECHANICAL PROPERTIES
OF MELIA AZEDARACH L WOOD
RAMADAN A. NASSER
Department of Forestry and Wood Technology, Faculty of Agriculture, Al-Shatby, Alexandria
University
ABSTRACT
This study was carried out at the beginning of 2006 to
investigate the effect of sewage effluent on the chemical and
mechanical properties of the (Melia azedarach L) chinaberry
wood as well as to study the differences between juvenile and
mature wood in those properties. Six trees (9-years old) were
chosen from Melia azedarach L grown in southwest Alexandria
city (New Borg El-Arab). The small clear specimens from
juvenile and mature wood were prepared and tested according
to British Standard Specification. Three mechanical tests were
done namely static bending, compression parallel to grain and
Janka hardness. Based on extractive-free and the oven-dry
weight, cellulose, hemicellulose, lignin, and ash contents were
determined according to the standard methods. The results
indicated that using sewage effluent in irrigation significantly
increased cellulose, lignin, ash and extractives content of wood.
The decreased in hemicellulose content for the trees irrigated
with sewage effluent compared to tap water was not significant.
With exception for ash content, the effects of sewage effluent
irrigation on the chemical constituents of wood are quit low.
The highest effect of sewage effluent on chemical components
was obtained with ash content. Mature wood had significantly
higher average cellulose, hemicellulose and extractives contents
than juvenile wood. However, lignin and ash contents of
juvenile wood were significantly higher than mature wood.
Sewage effluent significantly increased wood specific gravity of
139
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
chinaberry. Sewage effluent had a notable better effect on all
mechanical properties of chinaberry wood especially modulus
of elasticity (MOE) as compared to tap water. Wood chemical
components were clearly correlated with each of modulus of
rupture (MOR), MOE and maximum crushing strength (Cmax).
There were negative correlations between hemicellulose content
and each of MOR, MOE and Cmax. However, other relations
between were positive.
INTRODUCTION
Many developing countries, including Egypt, do not posses adequate forest
reserves to cover their needs for fuel wood, industrial wood, sawn wood, and
wood-based composition panels. The annual wood and wood products exportation
in Egypt is estimated at 640 million dollars in 2004 (Ali, 2005) and 874 million
dollars in 2007. Planting fast growing trees is one of different strategies which
used to reduce the annual import of wood products. In order to meet increasing
demand, Egypt has been planted fast growing tree species and used sewage
effluent to irrigate forest trees as it is not recommended for edible crops. Water is
becoming an increasingly scare resource in many arid and semi-arid regions. It is
essential to develop water resources through untraditional ways (Selim, 2006).
Reuse of wastewater is one of these resources. In the middle of the 19th century,
many European and North American cities adopted crop irrigation as their means
of wastewater disposal (Arar, 1999). The wastewater generated from Alexandria
City is about 1.5 million m3 per day and the expected amount by the year of 2020
is 2.5 million m3per day (Selim, 2006).
Many investigators have been concluded that wastewater, in addition to its
beneficial nutrients, also contains contaminants (pathogens, disease-causing
viruses, bacteria, protozoa and helminthes) and toxins (heavy metals) which are
toxic to both people and plants (Ralph and Black, 1998, Al-Jamal et al, 2002,
Hassan et al, 2003, Kayad et al, 2005, and Ali, 2005). So that, the reuse of
wastewater for irrigation trees, seems to be the most promising method. The safe
use of the wastewater after primary treatment is irrigating tree plantations,
forestlands, green belts around the cities and non-food crops. Most of these studies
140
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
were focused to detect the changes in the physical and chemical properties of soil
by use of sewage effluent (El-Nennah et al, 1982, Kanekar et al, 1993, Hassan et
al, 2003, and Ali, 2005). Other studies were investigating the effects of irrigation
with sewage effluent on the growth parameters of some forest trees, tree biomass
potential and allocation of its components (Kerr and Stopper, 1982, Hopmans et al,
1990, Ali, 2005, and Hassan et al, 2006). However, the effects of irrigation with
sewage effluent on the specific gravity, fiber length and volumetric shrinkage of
forest trees have been studied by many researchers (Szopa et al, 1977, Abohassan
et al, 1988, Kayad et al, 2005, Hassan et al, 2006) these properties were selected
because of their strong relationship with wood substances which used by wood
users to classify the quality of wood produced from trees. On the other hand, no
studies were conducted to evaluate the effect of irrigation with sewage effluent on
the mechanical properties of wood.
Some studies report that the sewage effluent treatment had a significant
effect on the specific gravity and fiber length of wood produced from different
wood species (Szopa et al, 1977, Ali, 2005 and Hassan et al, 2006). However,
Kayad et al (2005) on Melia azedarach L. wood indicated that sewage water had
slight effect on those properties but volumetric shrinkage increased significantly
from 13.4 to 14.73%. Abdel-Aal et al (2008) evaluated the effect of sewage sludge
application on chemical composition of Casuarina cunninghamiana grown in
Egypt. They found that the sewage sludge treatment increased extractive and ash
content.
Melia azedarach (chinaberry) is a fast growing and a deciduous hardwood
tree in the Meliaceae family, native to Himalayan region of Asia. It has been used
as a promising woody tree that grows up to 20 m high. Chinaberry wood is used
for turnery, furniture, decorative veneers, novelty items, boxes and chests
(Chudnoff, 1984).
Finally, chemical composition and mechanical properties of wood are the
important technological properties which assess wood users to suggest the proper
utilization of wood (Hygreen and Bowyer, 1982). Therefore, these technological
properties are essential to evaluate the suggesting proper utilization of wood.
Wood formed at an early age in a tree is commonly referred to as juvenile
wood and wood produced later is known as mature wood (Haygreen and Bowyer,
1982 and Roos et al, 1990). The effect of juvenile wood on softwood has been
141
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
extensively explored (Bendsen and Senft, 1986, McAlister and Clark, 1992 and
Abdel-Gadir and Krahmer, 1993), however, comparatively little research of
juvenile effects on hardwoods has been done (Roos et al, 1990 and Evans et al,
2000).
It would appear from this literature survey that controversy continues to
appear concerning the influence of sewage effluent irrigation on the chemical and
mechanical properties of wood. Greater knowledge of both juvenile and mature
wood properties in chinaberry as a hardwood species is needed. The work to be
reported here represents the first attempt to provide basic information regarding
this point. This information will help wood users to suggest the suitability of wood
for wood industries (i.e., pulp and paper industry and wood composite panels), fuel
and construction purposes.
The objectives of this study were firstly to investigate the effect of sewage
effluent on the chemical and mechanical properties of the chinaberry wood and
secondary to study the differences between juvenile and mature wood in those
properties. Finally the study aims to find the relationship between those properties.
MATERIALS AND METHODS
Nine years old trees with a straight trunk were randomly chosen from Melia
azedarach L trees (six trees) grown in two sites in southwest Alexandria city. For
more detail about plantation, management, site description, growth characters,
biomass production, analyses of wastewater and soil were reported in a study by
Kayad et al, (2005). The experiment was carried out at new Borg E-Arab city (310
000 N, 290 330 E). Sewage effluent used to irrigate the plantation was derived from
industrial and municipal sources. It treated primary, then stored in lagoons
temporarily before irrigation. In the control treatment, the trees were irrigated with
tap water. The analysis of wastewater used in the current study is presented in
Table (1).
142
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
143
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
After the trees were felled in the beginning of 2006, one 60-cm bolt in
length at about 140 cm from the ground level were removed. The two ends of the
bolts were coated with tar to prevent moisture losses. The bolts were then
transported to the Wood Testing Laboratory, Faculty of Agriculture, Alexandria
University. The bolts were then piled and machined green resembling the ASTM
D-134 (1989). From each bolt, two adjacent diametric strips (3*3 cm) were
removed. Each strip removed from each bolt was re-sawn longitudinally into four
sticks. Two sticks of them were near the bark (mature wood or outer zone) and the
others near the pith (juvenile wood or inner zone) according to McAlister and
Clark (1992). The specimens were stacked on pallets for air-drying in the
laboratory until the equilibrium moisture content (EMC) was reached.
Mechanical Testing Procedure:
The small clear specimens were prepared and tested according to British
Standard Specifications (BSS) No. 377 (1957). In this specification, the 2-cm
system of testing was used which one of the principle schemes accepted
internationally for the testing of small clear specimens. The performed tests are
listed in Table (1). All mechanical tests were carried out using Instron Universal
Testing Machine model 1195 at the Wood Testing Laboratory, Department of
Forestry and Wood Technology, Faculty of Agriculture, Alexandria University,
Egypt.
In static bending test, the load at proportional limit (PPL), maximum load
(Pmax) and deflection (y) were obtained from load-deflection curves, then the
modulus of elasticity (MOE), and modulus of rupture (MOR) were calculated
using the equations seen in Table (2). In compression parallel to grain, increasing
load was applied to the individual test specimens until a failure occurred and
maximum crushing load value was recorded, then the maximum crushing strength
(Cmax) was calculated (Table 2). On the other hand, Janka hardness test was
conducted in radial and tangential directions with ball diameter of 11.28 mm (100
mm2 projected area) and the hardness strength (Janka hardness number, JHN) was
calculated as maximum load (kN), which equal to maximum load (kN). The
dimensions of test specimens, loading rates and the calculated parameters from
each test are shown in Table (2).
144
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
Table 2. Dimensions of mechanical test specimens, loading rates and
calculated parameters for each test.
Test
Bending
Dimensions (cm)
Cross Section
Length
2x2
30
Loading
Rate
6.6
Calculated parameters
MOR= (1.5 x Pmax)\(b x h2)
MOE= (PPL x L)\(4xDxbxh3)
Compression // to grain
2x2
6
0.63
Cmax=Pmax\(b x h)
Janka Hardness
2x2
8
6.3
JHN in radial direction
JHN in tangential direction
Pmax=maximum load, PPL=load at proportional limit, b and h=breadth and depth of specimen.
Loading rate is the rate of load applied in mm\min.
Specific gravity and moisture content of wood:
Upon the completion of the bending test, the moisture content and specific
gravity were determined by removing two pieces (2x2x1.5 cm) near the failure
point. Specific gravity was calculated based on oven-dry weight and volume at test
measured by dimensions using digital caliper to the nearest 0.01 mm. However,
moisture content was determined based on oven-dry weight basis.
Chemical analysis of wood:
After the mechanical tests were completed, each sample was divided into
small pieces and milled in a laboratory Wiley mill to obtain a 40-60 mesh meals.
Total extractives content was determine based on oven-dry weight of the wood
meals according to ASTM D-1105 (1989). Based on extractive-free and the ovendry weight of wood meal, cellulose, hemicellulose, lignin, and ash contents were
determined according to Nikitin (1960), Rozmarin and Simionescu (1973), ASTM
D-111 (1989), and NREL (1994), respectively.
Statistical analysis:
The data were analyzed using split plot design. In addition, Duncan’s
multiple range test was used in order to examine the significance of differences
among the mean values of chemical and mechanical properties using the least
significant rang at 95% level of confidence (LSR0.05) when significant differences
were revealed by Statistical Analysis System (SAS) Program. In the second stage
of this analysis and to establish the relationship between each of mechanical
property as dependent variable versus each of chemical components as
independent variables, multiple regressions were used to reach the full model.
Then, the best reduced model representing the relationship studied was extracted
145
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
from the full model using a type of backward elimination procedures (Snedecor
and Cochran, 1967). The choice of the best reduced model was based on the
significant of each terms as well as coefficient of determination, R2 (Draper and
Smith, 1967). Simple regression analysis were also undertaken in order to have an
indication of the trend of relation between each of independent variables and
mechanical properties.
RESULTS AND DISCUSSION
Effect of sewage effluent on wood chemical constituents
Basic information concerning the effect of sewage effluent irrigation on
wood properties is little and limited. The current study is an attempt to provide this
information regarding some of the important wood properties of chinaberry lumber
which related to wood quality. In the present study, the statistical effect of sewage
effluent on chemical constituents of chinaberry wood was small, but highly
significant with exception for hemicellulose content which was not significant.
The mean values for the chemical constituents of the chinaberry wood as
affected by irrigation treatments are shown in Table (3). It can be seen from this
table that the sewage effluent significantly increased cellulose, lignin, ash and
extractives contents of wood. The decreased in hemicellulose content for the trees
irrigated with sewage effluent compared to tap water was not significant (24.04%
vs. 24.20% for control).
Table (3) and Fig (1) showed that sewage effluent irrigation gave higher
mean values of cellulose (42.41%), lignin content (33.36%) and ash content
(0.468%) compared to control treatment (tap water). The increase in cellulose
content at sewage effluent irrigation may be due to increase in latewood compared
to earlywood or thicker fiber walls especially in S2 layer (Abohassan et al., 1988).
The increased in cellulose, extractives and ash contents of wood as affected
by sewage effluent is in agreement with those obtained by Kherallah (1982) on
Eucalyptus camaldulensis and Abdel-Aal et al (2008) on Casuarina
cunninghamiana. They found that plantation irrigated with sewage effluent
contained significantly higher extractives, cellulose and ash contents. Contrary, the
significant increase in lignin content in the current study with sewage effluent
irrigation (33.36% vs. 32.54% for control) is disagreement with Abdel-Aal et al
(2008) who found that irrigated of Casuarina cunninghamiana trees with sewage
146
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
sludge slightly decreased the lignin content (28.98%) as compared to control
treatment (29.18%).
The insignificant decreased in hemicellulose content in the present work is
disagreement with Kherallah (1982) who reported a highly significant decrease of
hemicellulose in Eucalyptus camaldulensis irrigated by sewage effluent (28% vs.
31.0% for control) and Abdel-Aal et al (2008) who found the same trend in
Casuarina cunninghamiana (25.27% vs. 27.70% for control).
With exception for ash content and using the change percentage of wood
chemical constituents to tap water (control), it can be noticed from Table (3) that
the effects of sewage effluent irrigation on the chemical constituents of wood are
quit low, which ranged between 2.46% to 6.60% for lignin and extractives
contents, respectively. The highest effect of sewage effluent on chemical
components was obtained with ash content which increased from 0.39% to 0.47%
with the change percent of 17.52%. These results are in agreement with the
conclusion of Kayad et al (2005) who reported that although sewage water
enhanced the growth of chinaberry trees it had slight effect on wood properties.
They concluded that wood taken from trees irrigated by sewage effluent did not
differ much than normal wood that irrigated with tap water. Chemically and from a
practical point of view, our results demonstrated that although trees irrigated by
sewage effluent had a significant effect on the chemical components of chinaberry
but wood taken from trees irrigated by sewage effluent did not differ much than
normal wood that irrigated with tap water with exception for ash content.
Table 3: Effects of sewage effluent irrigation on wood chemical
components
Chemical Components (%)*
Cellulose content
Hemicellulose content
Lignin content
Extractive content
Ash content
Irrigation treatments
Control (Tap
Sewage
water)
effluent
40.46 (1.95)
42.41 (2.34)
24.20 (0.60)
24.03 (0.72)
32.54 (2.71)
33.36 (2.50)
11.74 (0.73)
12.57 (0.88)
0.386 (0.06)
0.468 (0.09)
Difference**
(%)
LSR0.05
4.60
2.46
6.60
17.52
0.32
NS
0.26
0.03
0.26
*
Each value is an average of 18 specimens.
** The difference between tap water and sewage effluent values as a percent of the later.
LSR0.05 is least significant rang at 5% level of probability by Duncan Multiple Test.
NS: Not significant.
( ) Values between parentheses are standard deviations.
147
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Control
Vol.7 (3)2008
Sewage
45
40
Percentage
35
30
25
20
15
10
5
0
Cellulose
Hemicellulose
Lignin
Extractive
Chemical Components
Fig. 1. Wood chemical components (%) as affected by sewage effluent irrigation
Chemical compositions of juvenile and mature wood as affected by sewage
effluent
Based on fundamental differences in the structure and properties of the wood,
the tree stem can be characterized as two regions, juvenile and mature (Panshin
and Zeeuw, 1980). Juvenile wood (core wood) is found in both softwoods and
hardwoods, and is usually of lower quality than mature wood (Hygreen and
Bowyer, 1989).
The mean values of wood chemical components for juvenile and mature
wood of chinaberry, and the relative differences between them expressed as a
percentage of the mean mature value, are tabulated in Table (4). It can be seen
from this Table and Fig. (2) that the mature wood had significantly higher average
cellulose (43.48%), hemicellulose (24.70%) and extractives (12.92%) contents
than juvenile wood (39.40, 23.52 and 11.39%, respectively). However, lignin and
ash contents of juvenile wood were significantly higher than mature wood and the
relative differences between the two types of wood were 16.46 and 34.62%,
respectively. The results indicated that ash content exhibited the largest difference
between juvenile and mature wood, 34.62 percent, while hemicellulose content
148
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
exhibited the least difference between the two types of wood, where the juvenile
wood was 4.78 percent lower than the mature wood.
These results are in agreement with Bendsen (1986) who reported that
juvenile wood had the lowest extractives and lignin contents and the highest
cellulose content as compared to mature wood.
Table 4: Properties of juvenile and mature wood of Melia azedarach L.
Difference**
Wood chemical
Maturity of wood
(%)
.components (%)*
Juvenile wood
Mature wood
Cellulose content
39.40B (0.95)
43.48A (1.27)
10.30
Hemicellulose content
23.52B (0.26)
24.70A (0.29)
4.78
A
Lignin content
35.45 (0.44)
30.44B (0.68)
-16.46
Extractive content
11.39B (0.36)
12.92A (0.54)
11.84
A
Ash content
0.490 (0.07)
0.364B (0.05)
-34.62
*
Each value is an average of 18 specimens.
** The difference between the juvenile and mature wood values as a percent of the
later.
Negative values mean adverse effect.
( ) Values between parentheses are standard deviations.
Values with the same letter in the same row do not vary significantly at 0.05 level of
probability according to Duncan’s Multiple Range Test. NS: not significant.
149
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Juvenile
Vol.7 (3)2008
Mature
45
40
Percentage
35
30
25
20
15
10
5
0
Cellulose
Hemicellulose
Lignin
Extractive
Chemical Component
Fig. 2. Wood chemical components (%) of juvenile and mature wood of
chinaberry.
The interaction between irrigation treatments and maturity level of wood
indicated that juvenile and mature wood resulted from the trees irrigated by sewage
effluent had the highest average values of cellulose and extractives contents as
compared with those values obtained from trees irrigated by tap water. In the same
time, mature wood for each of tap water and sewage effluent irrigation gave the
highest cellulose and extractives content (Fig. 3).
150
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
Jevinel wood Mature wood
14
44
13
Extractives Content (%)
Cellulose Content (%)
Jevinel wood Mature wood
46
42
40
38
36
12
11
10
9
8
34
Tap water
Sewage effluent
Irrigation Treatments
Tap water
Sewage effluent
Irrigation Treatments
Fig. 3. Effect of sewage effluent irrigation on the cellulose (left) and extractives (right) contents
of juvenile and mature wood.
Effect of sewage effluent on physical and mechanical properties of wood
The mean values for the physical and mechanical properties of wood as
affected by irrigation treatments are shown in Table (5). The differences among
irrigation treatments, wood maturity levels and the interaction between them were
not significant (Table 5). It can be said that all test specimens in the current study
were about the same moisture content which ranged between 11.97 to 12.25%
without any significant differences. This means that all the specimens were
carefully conditioned before test and the specimens were reached the equilibrium
moisture content before test (about 12%).Therefore, the values of mechanical
properties i.e. MOR, MOE and Cmax were not adjusted for differences in moisture
content.
The results tabulated in Table (5) indicated that using sewage effluent
significantly increased wood specific gravity of chinaberry (0.595 vs. 0.55 for
control) and the difference between the two mean values was higher (7.56%), but
small than tap water. These results are in harmony with those of Szopa et al.
(1977) when they studying Quercus alba, Hassan (1996) on Leucaean
leucocephala and Kayad et al. (2005) on Melia azedarach, and Ali (2005) on
151
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
different wood species. They concluded that sewage effluent irrigation slightly
increased specific gravity of wood. In general, although most mechanical
properties of wood are closely correlated to density which has been demonstrated
by several investigators (El-Osta et al., 1981, Hermandez, 2007, and El-Sayed et
al., 2009), the small change observed in the current study in specific gravity is not
sufficient to account for the relatively large differences in the mechanical
properties observed due to irrigation treatments. This result is in agreement with
Roos et al. (1990) on Populus tremuloides and Korkut and Guller (2008) on Ostrya
carpinifolia. The large change in mechanical properties with increasing age may
reflect the combined effects of increasing specific gravity, cell dimensions, and
increasing fibril angle in the secondary cell wall (Roos et al., 1990).
It can be noticed from Table (5) that sewage effluent irrigation had a
significant effect on all the mechanical properties of wood. The results indicated
that mechanical properties of wood increased with trees irrigation by sewage
effluent. Modulus of elasticity (MOE) had the largest difference between the two
mean values of tap water and sewage effluent, 15.98%. there is a significant
difference between the two means of MOE for the trees irrigated with sewage
effluent (11413.5 N.mm-2) and the others, which irrigated with tap water (9589.3
N.mm-2) according to least significant rang by Duncan’s multiple test. The least
difference between the two irrigation treatments was obtained with Janka hardness
number (JHN) in radial and tangential directions (6.39 and 6.19%, respectively). It
can be seen from Table (5) that JHN in the radial direction was lower (4.72 vs.
5.03 kN for control) than those values in the tangential direction (5.53 vs. 5.17 kN
for control). The data in Table (5) indicated that trees irrigated with sewage
effluent gave higher mean values of modulus of rupture, MOR, (118.2 N.mm-2)
and maximum crushing strength, Cmax, (47.7 N.mm-2) as compared to trees
irrigated with tap water (106.2 and 42.8 N.mm-2, respectively).
Based on the above results, it can be concluded that sewage effluent had a
notable better effect on all mechanical properties of chinaberry wood especially
modulus of elasticity (MOE) as compared to tap water. In the main time, this study
is the first attempt made to provide basic information regarding the effect of
sewage effluent on mechanical properties of wood.
152
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
Table 5: Physical and mechanical properties of wood as affected by
sewage effluent irrigation
Irrigation
.treatments
Tap water (Control)
MOR
(N.mm-2)
106.2
(16.5)
Sewage effluent
118.2
(15.5)
Relative Difference*
10.15
LSRo.o5
4.6
MOE
(N.mm-2)
9589.3
(2009)
11413.5
(2039)
15.98
377.8
Cmax
(N.mm-2)
42.8
(4.2)
47.7
(4.8)
10.16
1.3
JHN (kN) in
Tangential
Radial
5.17
4.72
(0.91)
(0.90)
5.53
5.03
(0.98)
(0.92)
6.39
6.19
1.14
0.97
MC
(%)
12.25
(0.58)
11.97
(0.17)
-2.34
NS
SG
0.550
(0.04)
12.25
(0.58)
7.56
0.012
*
Each value is an average of 18 specimens.
** The difference between tap water and sewage effluent values as a percent of the later.
+ SG is based upon volume at test and oven-dry weight.
LSR0.05 is least significant rang at 5% level of probability by Duncan Multiple Test.
NS: Not significant.
( ) Values between parentheses are standard deviations.
Physical and mechanical properties of juvenile and mature wood:
The mean values of physical properties and mechanical test data for juvenile
and mature wood and the relative differences between them as a percentage of the
mean mature wood are given in Table (6).
Table 6: Physical and mechanical properties of juvenile and mature
wood
Maturity of
.wood
Juvenile wood
MOR
MOE
Cmax
JHN (kN) in
MC
Tangential
(N.mm-2) (N.mm-2)
(N.mm-2)
Radial
(%)
SG
B
B
B
B
B
A
98.0
8605.1
41.4
4.44
4.00
12.15
0.523B
(8.6)
(1166)
(2.8)
(0.23)
(0.22)
(0.31) (0.02)
Mature wood
126.4A
12397.6A
49.1A
6.26A
5.74A
12.07A 0.621A
(9.4)
(992)
(3.4)
(0.26)
(0.21)
(0.56) (0.04)
Relative Difference** 22.47
30.59
15.68
29.07
30.31
-0.66
15.78
*
Each value is an average of 18 specimens.
** The difference between the juvenile and mature wood values as a percent of the later.
( ) Values between parentheses are standard deviations.
Values with the same letter in the same row do not vary significantly at 0.05 level of
probability according to Duncan’s Multiple Range Test.
It can be seen that for all mechanical properties of wood, mature wood had
the highest values and the least average values was obtained for juvenile wood and
the differences between them were significant. The mean values of MOR, MOE
153
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
and Cmax for mature wood were 126.4, 12397.6 and 49.1 N.mm-2, respectively. The
largest differences between juvenile and mature wood were obtained for MOE, and
Janka hardness number in radial and tangential directions (30.59, 29.o7 and 30.31
%, respectively). However, maximum crushing strength (Cmax) exhibited the least
difference between the two types of wood, 15.68%. The same result was reported
by Roos et al (1990) in quaking aspen (Populus tremuloides Michx.). Generally,
these results are in harmony with the finding of the conifers and hardwoods
previously studied (Schniewind and Gammon, 1989 and Roos et al, 1990). These
results permitted the discrete separation of juvenile and mature wood material was
needed due to the presence of significant differences between them.
Relationships between chemical components and mechanical properties:
The correlation coefficients matrix among each of physical, mechanical and
chemical properties of juvenile and mature wood are summarized in Table 7.
Examination of these simple correlation relationships for juvenile wood revealed
that good correlations (r= 0.47 to 0.96, p<0.01) were found between all
mechanical properties and each of wood chemical components. These coefficients
were significant or highly significant. This means that wood chemical components
were clearly correlated with each of MOR, MOE and Cmax. There were negative
correlations between hemicellulose content and each of MOR, MOE and Cmax.
However, other relations between each of chemical components and mechanical
properties were positive correlations. These results are in agreement with those of
El-Osta et al (1981) and El-Sayed et al (2009). For mature wood, it can be noticed
the same trend which obtained for juvenile wood except the correlation
coefficients belong to hemicellulose and ash contents were not significant (Table
7).
Extractives content showed significant positive correlation with each of
mechanical properties of either juvenile (r= 0.55 to 0.83) or mature wood (r= 0.50
to 0.89) as shown in Table (7). This means that the higher the extractives content
of wood the greater the mechanical properties. These results are in harmony with
the conclusion reached by many authors (El-Osta et al, 1981, Junior and Moreschi,
2003, Korkut and Guller, 2008 and El-Sayed et al, 2009) which led them to
suggest that extractives have an important role in reinforcing the cell walls.
Grabner et al, (2005) reported that sapwood extraction had a minor effect on the
154
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
mechanical properties, while in heartwood the effect was great. This affirms that
removal of high extractives contents of Ceteris paribus had a significant
consequence on Cmax and MOE. On the other hand, our result is disagreement with
Badran and El-Osta (1977) and Al-Mefarrej (1985). The former concluded that
extractive content did not affect the maximum crushing strength significantly and
the later found that the extractives content of Tamarix aphylla was not significant
correlated with bending strength parameters (MOR and MOE). This disagreement
may be attributed to the fact that exact location of extractives in wood tissues is not
well defined. If the extractives were located on the lumen surface of cell wood the
major repository in wood structure, they would not be expected to influence
strength (Badran and El-Osta, 1977). However, if these extraneous substances
were to be located within the cell wall structure, i.e., the amorphous regions, then
their influence on strength properties would be considerably pronounced (El-Osta,
1981). Hernandez (2007) concluded that the differences of mechanical properties
of wood should be explained both density and presence of extractives.
There were significant positive correlations between wood specific gravity
(SG) either for juvenile or mature wood and each of mechanical properties of
wood (Table 7). Good correlations were found (r= 0.57 to 0.90 for juvenile wood
and 0.67 to 0.91 for mature wood). As a general rule, the relationship between
wood SG and mechanical properties varies according to the considered properties
and to the different wood species, but in most cases it is linear. With increasing
SG, strength also increases and this is because SG is a measure of the wood
substance contained in a given volume (Tsoumis, 1999). These results are in
agreement with Arganbright (1971), El-Osta et al (1981), Schniewind and
Gammon (1986) and Pometti et al (2009). They concluded that strength properties
of wood are closely correlated with specific gravity and the higher the specific
gravity the greater the strength.
In the second stage of this analysis, multiple regressions were used to reach
the full model. Then, the best reduced model representing the relationship studied
was extracted from the full model using a type of backward elimination procedures
(Snedecor and Cochran, 1967). The choice of the best reduced model was based on
the significant of each terms as well as coefficient of determination, R2 (Draper
and Smith, 1967).
155
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
156
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
The multiple regression equations in reduced model for each of the
mechanical properties versus each of the variables of the chemical components of
juvenile and mature wood as well as all wood combined are presented in Table (8).
It is clear from the data in this table that after the elimination of non significant
variables based on the test of each partial regression coefficient (R2) from the full
model, all regression equations in the table account 67.9% to 96.5% of the total
variation on all mechanical properties studied herein (Table 8). It is clear that these
equations were the best reduced models to describe the total variations of each of
the mechanical test data i.e., MOR, MOE,.. etc in the current study. It can be seen
also that for the same mechanical property, there was a differences between the
equations which explained the variations according to type of wood (juvenile,
mature or combined). These results permitted the discrete separation of juvenile
and mature wood for further research. This finding is in agreement with the
conclusion of Roos et al (1990).
Simple regression analysis revealed that the coefficients of determination
(R ) between SG and each mechanical property range from 0.32 to 0.81 for
juvenile wood and from 0.45 to 0.83 for mature wood. This means that even for
statistically significant regressions, 32% up to 83% of the total variation in
mechanical properties can be explained by SG variation. Some of these relations
which have relatively high degree of association between specific gravity and
some of the mechanical test parameters are plotted in Figs. 4-6. It can be seen from
these figures that specific gravity is a good indicator to explain and detect the
mechanical properties of wood. These results are in agreement with voluminous
researches carried out to study the relationship between SG and mechanical
properties (El-Osta, 1985, Schniewind and Gammon, 1986 and Pometti et al,
2009).
2
157
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
Table 8. Regression equations (reduced models+) and coefficient of
determination (R2) of juvenile wood, mature wood and
all wood combined
Property
(Y)
MOR
MOE
Cmax
JHN radial
JHN
tangential
Wood type
Juvenile
Mature
Combined
Juvenile
Mature
Combined
Juvenile
Mature
Combined
Juvenile
Mature
Combined
Juvenile
Equation
R2
Y= 39.05 + 120.4Ash**
Y= 391 – 12.62 Hem* + 128.6Ash**
Y= 91.22 -4.30Lig** +10.63Ext** +78.49 Ash**
Y= -49066 + 1058Lig* + 1768Ext**
Y= 17658+414Cell*–900Hem*–614Lig*+1366Ext*
Y=-5095.0 -305.8Lig** +1914.4Ext** +5634.4Ash**
Y = -148.3 +4.55Lig** +2.50Ext**
Y= -94.3 + 4.71 Lig**
Y = 3.07 – 1.18 Hem* +5.80 Ext**
Y = -10.96 + 0.30 Lig* + 0.48 Ext** – 2.34Ash*
Y = 2.59 + 0.18 Ext* + 2.10 Ash*
Y =4.51 - 0.18 Lig**+ 0.517Ext**
Y = -23.3 +0.59 Hem**+ 0.37 Lig* + 0.37 Ext*
0.867
0.794
0.868
0.770
0.939
0.940
0.933
0.909
0.903
0.650
0.681
0.965
0.679
Mature
Y = -1.14 + 0.10 Cell* + 0.39 Ext* – 2.0Ash*
0.844
Combined
Y = -0.76+0.13Cell*-0.09Lig**+0.37Ext**-0.51Ash*
0.965
+ Carried out using least square method a stepwise elimination technique (Draper
and Smith, 1967).
Cell: Cellulose Hem: Hemicellulose
Lig: Lignin. For other code see Table 1.
*, ** Significant differences at 0.05 and 0.01 probability levels, respectively.
158
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
Juvenile
MOR = -104.21 + 386.41SG
R2 = 0.81
150
Mature
Modulus of rupture, N.mm2 (MOR)
Modulus of rupture, N.mm2 (MOR)
120
110
100
90
80
0.5
0.52
0.54
0.56
Specific gravity (SG)
0.58
140
MOR =-14.79 + 227.19SG
2
R = 0.82
130
120
110
100
0.54
0.56
0.58
0.6
0.62
0.64
0.66
0.68
0.7
Specific gravity (SG)
Fig. 4. Relationship between modulus of rupture (MOR)
and specific gravity (SG).
10500
15000
Juvenile
MOE = -16422 + 47829 SG
R2 = 0.68
9500
8500
7500
6500
0.5
0.51
0.52
0.53
0.54
0.55
Specific gravity (SG)
0.56
0.57
0.58
Modulus of elasticity, N.mm2 (MOE)
Modulus of elasticity, N.mm2 (MOE)
11500
Mature
MOE = -829.9 + 21285 SG
2
R = 0.64
14000
13000
12000
11000
10000
0.55
0.57
0.59
0.61
0.63
0.65
Specific gravity (SG)
Fig. 5. Relationship between modulus of elasticity (MOE)
and specific gravity (SG).
0.67
0.69
159
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
56
49
Mature
Maximum crushing strength, N.mm2 (Cmax)
Maximum crushing strength, N.mm2 (Cmax)
Juvenile
47
Cmax = -14.28 + 106.45 SG
R2 = 0.57
45
43
41
39
37
35
0.5
0.52
0.54
Specific gravity (SG)
0.56
54
52
Cmax = 11.35 + 60.705 SG
R2 = 0.46
50
48
46
44
0.58
42
0.55
0.57
0.59
0.61
0.63
0.65
0.67
0.69
0.71
Specific gravity (SG)
Fig. 6. Relationship between maximum crushing strength (Cmax)
and specific gravity (SG).
CONCLUSIONS
123-
4-
5-
Based on the results of the current study on the effect of sewage effluent on
the chemical and mechanical properties of the chinaberry wood as well as the
differences between juvenile and mature wood in those properties, the following
conclusions are drawn:
The effect of sewage effluent on wood chemical constituents was small, but highly
significant with exception for hemicellulose content which was not significant.
Sewage effluent significantly increased cellulose, lignin, ash and extractives
contents of wood and decreased hemicellulose content.
With exception for ash content, the effects of sewage effluent irrigation on the
chemical constituents of wood are quit low, which ranged between 2.46% to
6.60% for lignin and extractives contents, respectively.
The highest effect of sewage effluent on chemical components was obtained with
ash content which increased from 0.39% to 0.47% with the change percent of
17.52%.
Our results demonstrated that although trees irrigated by sewage effluent had a
significant effect on the wood chemical components but wood taken from trees
160
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
irrigated by sewage effluent did not differ much than normal wood that irrigated
with tap water with exception for ash content.
6- For all mechanical properties, mature wood had the highest values while the least
average values was obtained for juvenile wood and the differences between them
were significant
7- Separation of juvenile and mature wood material was needed due to the presence
of significant differences between them.
8- Good correlations (r= 0.47 to 0.96, p<0.01) were found between all mechanical
properties and each of wood chemical components.
9- Extractives content showed significant positive correlation with each of
mechanical properties of either juvenile or mature wood.
10- There were significant positive correlations between wood specific gravity either
for juvenile or mature wood and each of mechanical properties of wood.
11- Specific gravity variation can be explained from about 32% up to 83% of the total
variation in mechanical properties.
ACKNOWLEDGEMENT
I would like to express my gratitude to Dr. Mohamad A. Al-Aal for his
assistance. Thanks also due to Dr. Gaber R. Kayad for supplying the woody raw
materials used in this study.
REFERENCES
Abdel-Aal, M.A.M., A.S. Mohareb and N.D. Shetta (2008). Evaluation of sewage
sludge application on chemical composition of Casuarina cunninghamiana. J.
Agric. Sci. Mansoura Univ. 33 (7): 5197-5208.
Al-Mefarrej, H.A. (1985). Bending strength of Tamarix aphylla L. as related to specific
gravity and extractive content. M.Sc. thesis, College of Agriculture, King Saud
University, Riyadh, Saudi Arabia.
American Society for Testing Materials (1989). Standard test methods for
determination of lignin content of wood. ASTM D-111. Philadeliphia, Pa. U.S.A.
161
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
American Society for Testing Materials (1989). Standard test methods for
determination of extractives content of wood. ASTM D-1105. Philadeliphia, Pa.
U.S.A.
American Society for Testing Materials (1989). Standard test methods for preparing
small clear specimens of timber. ASTM D-134. Philadeliphia, Pa. U.S.A.
Abdel-Gadir, A.Y. and R.L. Krahmer(1993). Estimating the age of demarcation of
juvenile and mature wood in Douglas-fir. Wood and Fiber Sci. 25 (3): 242-249.
Abohassan, A.A.; I.E. Kherallah and S.A. Kandeel (1988). Effect of sewage effluent
irrigation regimes on wood quality of Prosopis juliflora grown in Riyadh region.
Arab Gulf J. Sci. Res. Agric. Biol. Sci. B6 (1): 45-53.
Ali, H.M. (2005). Effects of irrigation with sewage effluent on some trees. MSc. Thesis,
Department of Horticulture, Faculty of Agriculture, Kafr El-Sheikh, Tanta
University, Egypt.
Al-Jamal, M.S., T.W. Sammis, J.G. Mexal, G.A. Picchioni, and W.H. Zachritz
(2002). A growth-irrigation scheduling model for wastewater use in forest
production. Agricultural Water Management, 56: 57-79.
Arar, A. (1999). The future role of the use of sewage effluent for irrigation in the Near
East. CIHEAN-Options Mediterraneennes, 59-72.
Badran, O.A, and M.L.M. El-Osta. (1977). Influence of specific gravity and extractive
content on maximum strength of wood. Alex. J. Agric. Res. 25 (3): 541-548.
Bendsen, B.A., and J.F. Senft (1986). Mechanical and anatomical properties of in
individual growth rings of plantations-grown cottonwood and loblolly pine. Wood
and Fiber 18 (1): 23-28.
Bendsen, B.A. (1978). Properties of wood from improved and intensely managed trees.
Forest Prod. J. 28 (10): 61-72.
B.S.S. (1957). British Standard Methods of Testing Small Clear Specimens of Timber.
British Standrard Inst. London.
Chudnoff, M. (1984). Tropical timber of the world. USDA Forest Service Ag.
Handbook No. 607.
162
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
Draper, N. and D. Smith (1967). Applied regression analysis. New York, J. Wiley and
Sons.
El-Nennah, M., T.El-Kobbia, A. Shehata, and I. El-Gamal (1982). Effect of
irrigation loamy sand soil by sewage effluents on its content of some nutrients and
heavy metals. Plant and Soil 65: 289-292.
El-Osta, M.L.M. (1985). Some strength properties of Juniper southwest Saudi Arabia.
J. Coll. Agric., King Saud Univ., 7 (1): 103-112.
El-Osta, M.L.M., O.A. Badran, and E.M.A. Ajoung (1981). Crushing strength of the
three Sudanese tropical hardwoods in relation to specific gravity and lignin
contents. Wood Science 13 (4): 225-232.
El-Sayed, G.R., M.A.M. Abdel-Aal and R.A. Nasser (2009). Variations and
relationships between chemical consitituents and mechanical properties of black
polpar (Populus nigra L.) trees grown in two locations in Egypt. Egypt J. Appl.
Sc., 24 (4A): 268-283.
Evans, J.W., J.F. Senft, and D.W. Green (2000). Juvenile wood effect in red alder:
Analysis of physical and mechanical data to delineate juvenile and mature wood
zones. Forest Prod. J. 50 (7/8): 75-87.
Hassan, F.A. (1996). Effect of sewage effluent irrigation on growth, specific gravity and
fiber length of Acacia saligna and Leucaena leucocephala seedlings. J. Agric. Sci.
Mansoura Univ., 21 (11): 4093-4099.
Hassan, F.A., R.A. Nasser, S.S. Hegazy and N.A.A. El-Sayed (2006). Biomass
performance, specific gravity and fiber length for three tree species irrigated with
sewage effluent and the persistence and distribution of pollution indicator bacteria
in soil. Proceedings of First International Conference on Strategy of Botanic
Gardens, Bulletin of CAIM-Herbarium, Volume 7, May 10-12, 2006, Giza, Egypt.
Hassan, F,A., L.I.El-Juhany, A.A.El-Settawy, and M.S. Shehata (2003). Effects of
irrigation with sewage effluent on the growth and soil physical and chemical
properties of some forest trees. The Proceeding of the Second Conference of
Sustainable Agricultural Developments held at Al-Fayume Faculty of Agriculture,
Cairo University 8-10 May, Fayoum, pp: 300-311.
163
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
Haygreen, J.G. and J.L. Bowyer (1982). Forest Products and Wood Science. The
IOWA State Uni. Press/Ames., pp. 495.
Hermandez, E.R. (2007). Influence of accessory substances, wood density and
interlocked grain on the compressive properties of hardwoods. Wood Sci. and
Tech. 41 (2): 249-265.
Hopmans, P., H.T.L. Stewart, D.W. Flinn and T.J. Man (1990). Growth, biomass
production and nutrient accumulation by seven tree species irrigated with
municipal effluent at Wodonga, Australia. Forest Ecology and Management 30:
203-211.
Junior, G.B. and J.C. Moreschi (2003). Physical-mechanical properties and chemical
composition of Pinus taeda mature wood following a forest fire. Bioresource
Technology 87 : 231-238.
Kanekar, P., M.S. Kumbhojkar, V.Ghate, S. Sarnaik and A. Kelkar (1993).
Evaluation of Acacia nilotica (L.) DEL. and Casuarina equisetifolia Forest for
tolerance and growth on microbially treated dyestuff wastewater. Enviro.
Pollution. 81: 47-50.
Kayad, G.R., M.H. Khamis and S.S. Hegazy (2005). Effect of water quality on growth
and wood properties of Melia azedarach L. trees grown in southwest Alexandria
city. Egypt J. Appl. Sci., 20 (12), pp: 326-340.
Kerr, S.N., and W.E. Stopper (1982). Utilization of municipal wastewater and sludge
for forest biomass production on marginal and disturbed land. Pp. 75-87. Land
reclamation and biomass production with municipal wastewater and sludge. 7 Ref.
Pennsylvania State University, Pennsylvania, USA.
Kherallah, I. E.A. (1982). Chemical constituents and pulping characteristics of normal
and sewage irrigated Eucalyptus camaldulensis Dehn grown in Egypt. Ph.D.
thesis, Faculty of Agric., Alex. Univ. 200 pp.
Korkut, S. and B. Guller (2008). Physical and mechanical properties of European
Hophornbeam (Ostrya carpiniflolia Scop.) wood. Bioresource Technology 99:
4780-4785.
164
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
McAlister, R.H. and A. Clark (1992). Shrinkage of juvenile and mature wood of
loblolly pine from three locations. Forest Prod. J. 42 (7/8): 25-28.
Nikitin, V.M. (1960). ‘Himia drevesini I telliuloze’, Goslesbumiz_dat, M_L. Pg 233,
Chimia Lemnului SI A Celluloze I Vol I si II, 1973.
NREL (1994). Standard method for ash in biomass. CAT Task Laboratory Analytical
Procedure #005.
Panshin, A.J. and C. De Zeeuw (1980). Textbook of wood technology, 4th ed.
McGraw-Hill Book Co., New York, 722pp.
Panshin, A.J. and C. De Zeeuw (1980). Textbook of Wood Technology. McGraw-Hill
Series in Forest Resources, USA, ISBN:
Pometti, C.L., B. Pizzo, M. Brunetti, N. Macchioni, M. Ewens and B.O. Saidman
(2009). Argentinean native wood species: Physical and mechanical
characterization of some Prosopis species and Acacia aroma (Leguminosae:
Mimosoideae). Bioresource Technology 100: 1999-2004.
Ralph, E. H., and D. R. Black (1998). Sustainable production of short rotation forest
biomass crops using aqueous waste management systems. Biomass and Bioenergy,
15 (1): 75-81.
Roos, K.D., J.E. Shottafer, and R.K. Shepard (1990). The relationship between
selected mechanical properties and age in quaking aspen. Forest Prod. J. 40 (7/8):
54-56.
Rozmarin, G. and C. Simionescu (1973). Determining hemicellulose conten. Wood
Chemistry and Cellulose (Romanian) 2: 392.
Schniewind, A.P., and B. Gammon (1986). Strength and related properties of bishop
pine II. Properties of juvenile wood from young stems of various provenances.
Wood and Fiber Sci. 18 (3): 361-368.
Selim, M.M. (2006). Agronomic and economic benefits of reuse secondary treated
wastewater in irrigation under arid and semi-arid region. The 2nd International
Conference on Water Resources and Arid Environment, King Saud University,
Riyadh, Kingdom of Saudi Arabia, 26-29 November, 2006.
165
J. Agric.&Env.Sci.Alex.Univ.,Egypt
Vol.7 (3)2008
Snedecor, G.W., and W.G. Cochran (1967). Statistical methods. 6th ed. Iowa Univ.
Press, 593 pp.
Szopa, P.S., L.C. Tennyson, and E.A. McGinnes (1977). A note on effects of sewage
effluent irrigation on specific gravity and growth rate of white and red oaks. Wood
and Fiber 8 (4): 253-256.
Tsoumis, G. (1999). Science and technology of wood-structure. Properties, and
utilization. Chapman and Hall, New York.
‫‪166‬‬
‫‪J. Agric.&Env.Sci.Alex.Univ.,Egypt‬‬
‫‪Vol.7 (3)2008‬‬
‫الملخص العربً‬
‫تأثٌرات الري بمٌاه الصرف المعالج على المكونات الكٌمٌائٌة والصفات المٌكانٌكٌة لخشب‬
‫الزنزلخت ‪Melia azedarach L‬‬
‫رمضان عبد السٌد ناصر‬
‫قسم الغابات وتكنولوجٌا األخشاب‪ ،‬كلٌة الزراعة‪ ،‬الشاطبً‪ ،‬جامعة االسكندرٌة‬
‫أجرٌت تلك الدراسة اوائل علم ‪ 6002‬لبحث تأثٌر الري بمٌاه الصرف الصحً المعالج على الصفات‬
‫الكٌمٌائٌة والمٌكانٌكٌة لخشب الزنزلخت وكذلك لدراسة االختالفات بٌن الخشب الغٌر ناضج (الشاب) والخشب‬
‫الناضج فً تلك الصفات‪ .‬تم اختٌار ست أشجار (عمر ‪ 9‬سنوات) من أشجار الزنزلخت ‪Melia azedarach L‬‬
‫النامٌة فً موقعٌن جنوب غرب مدٌنة االسكندرٌة (مدٌنة برج العرب الجدٌدة وكنج مرٌوط)‪ .‬تم تجهٌز واختبار‬
‫عٌنات صغٌرة خالٌة من العٌوب من الخشب الغٌر ناضج والخشب الناضج تبعا ً للمواصفات القٌاسٌة البرٌطانٌة‬
‫(‪ .) BSS‬أجرٌت على العٌنات ثالث اختبارات مٌكانٌكٌة هً اختبار االنحناء االستاتٌكً‪ ،‬اختبار الضغط الموازي‬
‫لأللٌاف واختبار جانكا للصالدة ثم قدرت المكونات الكٌمٌائٌة للخشب من سٌلٌلوز‪ ،‬هٌمٌسٌلٌلوز ولجنٌن ورماد على‬
‫عٌنات خالٌة من المستخلصات وذلك تبعا ً للطرق القٌاسٌة‪ .‬اوضحت النتائج حدوث زٌادة معنوٌة فً محتوي الخشب‬
‫من السٌلٌلوز‪ ،‬اللجنٌن الرماد والمستخلصات نتٌجة الري بمٌاه الصرف المعالج بٌنما كان النقص غٌر معنوي فً‬
‫محتوى الخشب من الهٌمٌسلٌلوز نتٌجة الري بمٌاه الصرف مقارنة بالكنترول‪ .‬دلت النتائج إلى انه باستثناء محتوى‬
‫الخشب من الرماد‪ ،‬فان تأثٌر الري بمٌاه الصرف المعالج على محتوي الخشب من المكونات الكٌمٌائٌة كان قلٌالً وان‬
‫اعلى تأثٌر حدث فً محتوي الرماد حٌث زاد زٌادة معنوٌة وكبٌرة‪ .‬أعطى الخشب الناضج محتوى أعلى بصورة‬
‫معنوٌة فً السٌلٌلوز‪ ،‬الهٌمٌسلٌلوز والمستخلصات الخشبٌة مقارنة بالخشب الغٌر ناضج بٌنما كان محتوى الخشب‬
‫الغٌر ناضج أعلى معنوٌا ً فً كل من اللجنٌن والرماد مقارنة بالخشب الناضج‪ .‬دلت النتائج على ان جمٌع الصفات‬
‫المٌكانٌكٌة تحسنت نتٌجة الري بمٌاه الصرف المعالج خاصة معاٌر المرونة ‪ MOE‬مقارنة بالكنترول‪ .‬واظهرت‬
‫النتائج أن المكونات الكٌمٌائٌة ارتبطت بصورة جٌدة وواضحة بكل من معاٌر الكسر‪ ،MOR‬الـ ‪ MOE‬والمقاومة‬
‫القصوى فً الضغط ‪ Cmax‬كما وجدت عالقة ارتباط عكسٌة بٌن اي من تلك الصفات وبٌن محتوي الخشب من‬
‫الهٌمٌسلٌلوز فً حٌن كانت باقً العالقات معنوٌة موجبة‪ .‬وخلصت الدراسة إلى ان الري بمٌاه الصرف المعالج ٌؤثر‬
‫معنوٌا ً ولكن بصورة قلٌلة على محتوى الخشب من المكونات الكٌمٌائٌة باستثناء محتوى الخشب من الرماد فً حٌن‬
‫ٌؤثر الري بمٌاه الصرف معنوٌا ً وبصورة مقبولة على الصفات المٌكانٌكٌة للخشب‪ .‬كما اشارت الدراسة إلى ضرورة‬
‫الفصل بٌن الخشب الغٌر ناضج والخشب الناضج نظرا ً لوجود اختالفات معنوٌة وكبٌرة فً التركٌب الكٌمٌائً‬
‫والصفات المٌكانٌكٌة‪.‬‬